Apparatus for sealing a bore hole casing



May l0, 1955 s. M. zANDMER APPARATUS FOR SEALING A BORE HOLE CASINGFiled June 18, 1952 Fiel INVENTOR ATTORNEY United Statesl Patent()APPARATUS FOR SEALING A BORE HOLE CASING Solis Myron Zandmer, Calgary,Alberta, Canada Application June 18, 1952, Serial No. 294,251

6 Claims. (Cl. 166-100) This invention relates to improved apparatus forsealing a bore hole casing or liner in a bore hole, and moreparticularly to novel apparatus for providing ducts for the ow of iluidsbetween selected earth strata and the interior of a bore hole casing orliner.

Heretofore, bore hole casings have been set in drilled bore holes by acementing process in which fluid cement is forced down through thecasing and then upwardly around -the outside of the lower portion of thecasing to fill the space between the outside of the casing and thesurrounding earth. It has then been customary to perforate the casingand the surrounding cement at the levels of producing strata by means ofhorizontal drilling or by means of gun-type perforators which re aprojectile through the casing and cement to form passagewaystherethrough. Said known methods and apparatus have created variousdifculties such as a shattering of the cement, destruction of thesealing vbond between the casing or liner and the cement, and theformation of cracks in the cement making said cement subject todestructive attack by acids subsequently introduced to acidize andimprove the ow of fluids from productive strata.

A novel method and apparatus for establishing communication betweenproducing strata and the interior of a cemented bore hole casing orliner is shown in my joint application Serial No. 285,201 filed April30, 1952, and the present application is a continuaton-in-part of saidearlier application.

It is an object of the present invention to provide improved apparatusfor establishing communication between producing strata and the interiorof a cemented bore hole casing or liner.

-It is another object of this invention to provide economical ductsbetween producing strata and a bore hole casing or liner which do notdamage in any manner the electiveness of a cement seal between thecasing or lliner andthe surrounding earth lformations.

It is a further object of this invention to provide a novel bore holecasing or linerconstruction having a movable duct-forming sleeve orduct, the sleeve or duct being extendable laterally from the casing orliner into contact with producing strata either before cement is appliedaround the casing or liner or while such cement is in a fluid condition.

. It is a further object of this invention to avoid puncturin`g orperforating a casing or liner after it has been sealed in cement andhence to avoid damaging the sealing cement or the bond between thecement and the bore hole casing or liner and/or the bond between thecement and the bore hole wall.

It is a still further object of this invention to provide a bore holecasing or liner with a plurality of lateral duct-forming devices atvarious levels operable ,by uid pressure to establish or position theducts between the casing or liner and different strata of thesurrounding limestone formations without damaging the seal betweenameten across between the outer surface of the casing 12 andJ the casingor liner and the surrounding formation and between the various levels orstrata.

Other objects and advantages of this invention will become readilyapparent from the following detailed description of a preferredarrangement of apparatus and its method of use. In the accompanyingdrawings forming a part hereof:

Figure 1 is a vertical section view, partly cut away and partlydiagrammatic of a bore hole provided with a casing sealed in accordancewith this invention.

Figure 2 is a fragmentary view, on an enlarged scale, taken on line 2--2of Figure 1 before the duct-forming device is laterally extended andbefore the application of sealing cement to the space between the casingand the wall of the bore hole.

Figure 3 is a fragmentary view similar to Figure 2 but showing theduct-forming device extended to the wall of the bore hole and set insealing cement.

Figure 4 is a fragmentary view similar to Figure 3 but showing theduct-forming device open to establish communication between a producingstratum and the interior of the hole casing or liner.

Referring to the drawings for the purposes of illustration, a bore hole10 is drilled in the earth or limestone 11 by any conventional drillingapparatus. In

boring wells through limestone formations, for example,

the bore hole 10 may be of approximately nine inches in diameter andwill have a substantially smooth and regular surface. A bore hole casingor liner 12 is positioned in the bore hole 10, and may be formed ofsteel or aluminum tubing of about seven inches outside di- This leavesan annular space about one inch the wall of the bore hole 10. The casingor liner 12 is sealed or set in the formation 11 by means of cement 13.The cement 13 may be Portland cement or any other composition orsettable plastic material not affected by oil, gas, or bore holetreating chemicals.

Earth formations 11 usually have a plurality of oil or gas producingstrata indicated in the drawings by the numeral 14. Some'of the strata14 may be more porous than other adjacent strata. The porosity of theindividother chemicals, it is desirable that the cement seal 13 betweenvarious strata be maintained unbroken so that upon application of acidsunder pressure there will 'be no leakage outside of the casing 12 fromone strata 14 to another strata 14 of greater porosity. In actualpractice the strata 14 may be found to be of relatively small thicknessand spaced only a few feet apart.

The section of well casing or liner 12 adjacent -thestrata 14 isprovided before its introduction into the bore hole with a plurality ofduct-forming devices 15 mounted in the wall of the casing 12 at levelsto correspond with: the indicated levels of the strata 14 to be tapped.'One'- such duct-forming device will now be describedv first With vreference to its original position illustrated in Figure `2.

The device 15 comprises a bushing 16 mounted in an opening in the casing12 by threads 17. The outer end of bushing 16 projects beyond the outersurface of casing 12 into the space between the casing 12 and the wallofthe borehole 10. The duct-forming devices may be spaced around thecircumference of casing 12 at the various levels to be tapped and serveas centering devicesv tending to keep the casing 12 approximatelycentered as it' is lowered into the bore hole 10. The 'outer surfaceofeach bushing may be provided with a recess -18.to permit the applicationof a Spanner wrench to screw the bushing into the threaded opening ofcasing 12. A ductforming sleeve-like member 19 is slidably mounted inthe bushing 16, and is initially provided with a closure disc 20 securedwithin the member. The member 19 has a peripheral flange 21 at its innerend engageable with an inwardly extending flange 22 on the outer end ofbushing 16 to limit the outward sliding movement of member 19. A disc 24having a restricted aperture 25 therethrough is secured in the inner endof bushing 16 by threads 26. A valve 27 is mounted on the outer face ofclosure disc 24 and acts as a check valve to prevent the back flow offluids or cement through the aperture 25 into the interior of the casing12. The valve 27 may be a resilient flap valve mounted by a screw 28, asillustrated, or may be a spring-pressed ball-type check valve or theequivalent.

The bushing 16 is preferably formed from aluminum or steel, the same ascasing 12. The sleeve 19 is preferably made from bronze. The closuredisc 20 and the apertured disc 24 are preferably die castings formed ofpot metal containing zinc or of any other metal or substance easilydissolved by the application of conventional bore hole treating acids.It is to be understood that suitable packing material such as rubber orother self-sealing materials may be secured to the outer periphery offlange 21 and/or to the inner periphery of flange 22 to prevent theleakage of fluids under pressure into the space between the sleeve 19and the bore of bushing 16. The valve 27 may be resiliently biasedagainst the aperture 2S to maintain the aperture closed until apredetermined internal fluid pressure is applied within the casing 12.

The sleeve member 19 is adapted to be moved from its initial positionwithin bushing 16, shown in Figure 2, to a final extended positionprojecting outwardly from the outer end of bushing 16, shown in Figure3, by the application of fluid under pressure within the casing 12.

When it is desired to project the duct-forming sleeve 19 into contactwith a porous stratum 14, fluid pressure is applied within the casingand flows through the aperture 25, opens valve 27, and engages theclosure disc 20 to push the sleeve 19 outwardly. The bottom of thecasing or liner 12 is initially closed by a releasable valve or plate30, to open the apertures 32 to the flow of plastic sealing cement 13under pressure from within the casing 12 outward and upward within thebore hole. The hollow portion of sleeve 19 may be initially filled withan acid soluble paste 33 to prevent the sleeve from becoming cloggedwith drill cuttings or other deleterious material within the bore holewhen the casing 12 is lowered and positioned therein. As shown in Figure3, sealing cement 13 is forced into the space between the outer sur- Yface of casing 12 and the inner surface of the bore hole 10.

The preferred method of operation will now be described. A bore hole 10drilled in an earth formation, such as limestone 11, is surveyed byconventional methods to determine both the porosity and the actual levelof the several porous strata 14 above the bottom of the bore 10. Acasing or liner 12 is vthen prepared with a plurality of duct-formingdevices 15 secured therein at levels corresponding to the levels of theseveral strata 14 to be tapped. The casing or liner 12 is then loweredinto the bore hole 10 until it engages the bottom and the ductformingdevices are opposite the strata 14 to be tapped. Fluid under pressure isthen pumped into the casing 12 until the pressure is great enough toopen valves 27 in duct-forming devices 15 and push the sleeve members 19outward until the outer end of each member 19 firmly engages the wall ofa porous stratum 14. Next, sealing cement 13 under a greater fluidpressure is forced into the casing so as to open or force downward thereleasable bottom closure 30 of the casing 12 from position 30a to aposition below the lateral passages 32, the fluid cement then passingthrough passages 32 and upwards filling the space between the outersurface of the casing 12 and the wall of the bore hole 10. The ductdevices 19 are surrounded by the cement 13 and subsequently providepassageways from the casing l2 to the strata 14 before the cement 13 ishardened and set. After the cement 13 has firmly set and become therebybonded to the outer surface of casing 12, to the wall of the bore hole10 and to the surfaces of the duct devices 15, the apertured disc 24,closure disc 20, and filler paste 33 may be dissolved away by theapplication of an acid solution which does not dissolve the aluminumcasing 12, the aluminum bushing 16 or the bronze duct-forming sleevemember 19. Conventional drilling tools may be used to cut away anycement remaining within the casing 12.

It will be apparent that the described method and apparatus providesnovel means for setting and forming ducts or passageways through thecasing 12 and cement 13, without in any way damaging the casing 12 orcracking or shattering the cement seal 13. It will also be apparent thatthe elimination of cutting or perforating the set cement seal eliminatesany damage to the sealing bond between the cement 13 and the casing 12and the bond between the cement 13 and the inner surface of the borehole 10. This feature is of great importance because it prevents anysubsequent leakage along the bore outside of the casing 12 of acidsapplied to acidize or treat a given strata 14, and hence eliminatespossible loss of treating chemicals into the more porous strata. The useof packers within the casing 12 to confine the treating chemicals to adesired stratum is well known. It will also be apparent that theduct-forming devices used with the above-described method may vary indetails from the embodiment shown without departing from the scope ofthis invention as defined in the following claims.

I claim:

1. In apparatus for use in a bore hole traversing a porous stratum to betapped; a duct-forming device adapted to be supported by a bore holecasing, said device comprising supporting means mountable in the wall ofsaid casing and projecting outward therefrom, a hollow tubular membermovable outwardly in said supporting means to engage the outer end ofsaid member with said porous stratum, closure means carried by saidhollow member, and means carried by said supporting means defining anaperture providing communication between the interior of said casing andsaid closure means, said closure means being of a material dissolvableby chemical reaction.

2. In apparatus for use in a bore hole traversing a porous stratum to betapped; a duct-forming device adapted to be supported by a bore holecasing of smaller diameter than the diameter of said hole, said devicecomprising a supporting bushing mountable in the wall of said casing, ahollow tubular member slidably mounted in said supporting bushing formovement outwardly therein, the outer end of said hollow member beingopen for engagement with said porous stratum, closure means mounted inthe inner end of said member, and valve means mounted in said supportingbushing admitting fluid pressure from within said casing against saidclosure means, said closure means and a portion of said valve meansbeing of material dissolvable by chemical reaction with an acidsolution.

3. In apparatus for use in a bore hole traversing a porous stratum to betapped; a casing of smaller diameter than the diameter of said hole, aduct-forming device supported by said casing, said duct-forming deviceincluding a tubular member slidably mounted in an aperture through thewall of said casing and projecting outward of the inner wall of saidcasing, said tubular member being slidable outwardly from said casing toengage the outer end of said member with said porous stratum, anddissolvable closure means mounted within said tubular member, saidduct-forming device providing a duct from the interior of said casing tosaid porous stratum adapted to be embedded in sealing material in thespace between the exterior surface of said casing and the wall of saidbore hole, said closure means being of a material dissolvable bychemical reaction with bore hole acidizing solutions.

4. In 'apparatus for use in a bore hole traversing a porous stratum tobe tapped; a duct-forming device adapted to be supported by a bore holecasing, said device comprising a supporting bushing mountable in anaperture in the wall of said casing and projecting 0utward from theouter surface of said casing, a hollow tubular member mounted within andslidable outwardly in said bushing to engage the outer end of saidmember with said porous stratum, flanges on said bushing and on saidhollow member to limit the outward movement of said hollow member insaid bushing, a removable closure in said hollow member, and check valvemeans supported by said bushing inward of said hollow member andadmitting fluid pressure from within said casing to engage said closure,said closure and said valve means being ot a material dissolvable bychemical reaction with an acid solution.

5. In apparatus for use in a bore hole traversing a plurality of porousstrata to be tapped; an aluminum well casing adapted to be lowered intosaid bore hole, a plurality of lateral duct-forming devices supported bysaid casing at spaced intervals corresponding t0 the distance betweenstrata to be tapped, each of said duct forming devices comprising analuminum supporting bushing mounted in an aperture in the wall of saidcasing and communicating with the interior of the casing, and a bronzetubular member slidably mounted in said bushing for lateral movementoutwardly into contact with the wall of said one of said strata, and aclosure disc of metal containing zinc secured in said tubular member anddissolvable by a bore hole acidizing solution.

6. ln apparatus for use in a bore hole traversing a plurality of spacedporous strata to be tapped; a Well casing of smaller diameter than saidbore hole and adapted to be lowered into said bore hole, a plurality ofduct-forming devices supported by said casing at spaced intervalscorresponding to the distance between said porous strata to be tapped,each of said duct-forming devices comprising a tubular bushing mountedin an aperture in the Wall or said casing and communicating with theinterior of said casing, a tubular member slidably mounted in saidbushing for movement outward to engage the outer end of said tubularmember with one of said porous strata, a closure disc mounted in saidtubular member and being of a material dissolvable by a bore holetreating acid solution, and a filler material filling the outwardportion of said tubular member and also dissolvable by said acidsolution.

References Cited in the le of this patent UNITED STATES PATENTS1,410,827 Muehl Mar. 28, 1922 2,196,652 Baker Apr. 9, 1940 2,330,144Powers Sept. 21, 1943 2,546,669 Kirby Mar. 27, 1951

